Black51

^^^Is that why you pay so damn much for a Merc??

DanaT

Hope it has better reliability those renound French auto makers such a Renault and Peugeot!

I mean come on, how much more stylish can one get than a Renault Espace?? Last turbo diesle Espace I drove, with all its style, power, and high speed stability, it made me wonder how Porsche can even sell a 911. It was such a great car that on Autobahns, it made 140 feel like 280. Fortunately, the Espace didn't have my wife complaining I was driving too fast...

-Dana

Laust Pedersen

Here is a reference to SAAB’s VC engine:
http://www.youtube.com/watch?v=oxR-3Un6WkU

The goal for this pursuit is better fuel economy, since the thermodynamic efficiency increases with the compression ratio (CR). The formula is relatively simple, namely:

η = 1 - (1/r)^(k-1) where (^ is the exponent)
η is the thermodynamic efficiency
r is the compression ratio
k is the adiabatic gas constant.

The upward limit of the CR is determined by detonation at WOT. So if the CR can be increased at lower loads there is an efficiency gain (= fuel saving).

The typical design solutions to the Variable Static (geometric) Compression add maybe 30% complexity, weight and cost to an engine for maybe a 5% to 10% fuel saving, depending on driving cycle, which makes it commercially questionable.

However what is of real interest is the dynamic compression ratio, related to the ratio of the pressures just after scavenging and just before combustion start.
That can also, and much cheaper, be controlled by fully variable cam timing (duration, position and lift). Many actuation mechanisms have been tried such as fully electromagnetic and fully hydraulic, but I believe BMW was the first to make idea successful using a (el-motor actuated) mechanical system, which also acts as the throttle:
http://www.youtube.com/watch?v=RE5Tx47-b24&NR=1

So there you go: the variable compression ratio engine is already in use.

Laust

Feliks

Very beautifully presented idea.
But the problem is not with the control valve, but in the zaworze.Poped.
Heats up beyond measure, and you can not get a high compression ratio.
* Here are some examples of what happens afterwards. And with the precision control valve, you can only dream.



http://www.youtube.com/watch?v=_REQ1...eature=related

















Regards Andrew

Feliks

My 6 cylinder boxer..




Can have two times less cubic capacity, because that is two times smaller turnover at the flywheel....
and the turnover of the top of the piston can be two times bigger...

as a result we have the same power as the traditional engine..

Andrew